Two servers would be less reliable than one (with three you could have one failure and continue with the other two, with two the system would stop after one). Some people have used three (there are some things that won't work with three, depending on precise versions of applications and dlls) but I do not recommend it even if you don't use the affected applications.
Two servers would be less reliable than one (with three you could have one failure and continue with the other two, with two the system would stop after one). Some people have used three (there are some things that won't work with three, depending on precise versions of applications and dlls) but I do not recommend it even if you don't use the affected applications.